Since a microlens for an imaging device such as a charge coupled device (CCD) can form mainly fine patterns, the microlens can produce a high-definition imaging device, so that the microlens is produced using a method of forming patterns by a photoresist. In this method, by applying a resist composition containing a polymer resin and a sensitizer on a substrate to make a film and then by patterning and developing by a photolithogaraphic method, one pattern is formed to produce a microlens. Generally, the related-art material has no heat resistance sufficient for the application of the digital still camera.
There is disclosed a resist material using a polymer having as a repeating unit, hydroxystyrene, hydroxyvinylnaphthalene or hydroxyanthracene in which hydrogen atoms of hydroxy groups are partially replaced by acid unstable groups (see Patent Document 1).
There is disclosed a high refractive index resin for optical materials having heat resistance and containing a copolymer obtained by copolymerizing 2-vinylnaphtalene with a single type or a plurality of types of vinyl-based monomer capable of being radical-polymerized (see Patent Document 2).
[Patent Document 1]
Japanese Patent Application Publication No. JP-A-2005-114968
[Patent Document 2]
Japanese Patent Application Publication No. JP-A-8-53517